Non-plane wave communication is a new area of communications that may provide increased bandwidth and security for over-the-air communications. As is well known, a plane wave is an electromagnetic wave having a constant phase wave front that is substantially planar. Non-plane waves (or “twisted waves”), on the other hand, are electromagnetic waves having a surface of constant phase that forms a continuous spiral in space. It is believed that such waves will permit multiple orthogonal communication channels using the same transmit frequency to operate within the same space without interfering with one another (i.e., orthogonal modes). Preliminary tests have supported these theories. It is believed that twisted wave generation is possible over large portions of the electromagnetic spectrum, including both radio frequency (RF) and light portions of the spectrum.
Techniques for generating twisted waves have thus far been relatively unsophisticated. For example, early attempts at twisted wave generation have used modified parabolic dishes for wave generation. That is, a cut was made within a conventional parabolic dish and the dish was then physically bent into a shape that was believed to support twisted wave generation. In other approaches, antenna array techniques were used to support twisted wave generation. None of the techniques developed so far were able to produce reliable, accurate, and reproducible antennas. Thus, there is a need for better antennas capable of operating with twisted waves and also better techniques for designing and fabricating such antennas.